Roll chromium_revision 3966d2c..4df2d47 (361020:361029)

Change log: https://chromium.googlesource.com/chromium/src/+log/3966d2c..4df2d47
Full diff: https://chromium.googlesource.com/chromium/src/+/3966d2c..4df2d47

No dependencies changed.
No update to Clang.

TBR=
CQ_EXTRA_TRYBOTS=tryserver.webrtc:win_baremetal,mac_baremetal,linux_baremetal

Review URL: https://codereview.webrtc.org/1466963002

Cr-Commit-Position: refs/heads/master@{#10738}
diff --git a/DEPS b/DEPS
index db04d30..eb74500 100644
--- a/DEPS
+++ b/DEPS
@@ -6,7 +6,7 @@
 vars = {
   'extra_gyp_flag': '-Dextra_gyp_flag=0',
   'chromium_git': 'https://chromium.googlesource.com',
-  'chromium_revision': '3966d2ccc663169b68726c04255b8723f22521d5',
+  'chromium_revision': '4df2d47c986e15641bcea90198558ec88ca7c2dc',
 }
 
 # NOTE: Prefer revision numbers to tags for svn deps. Use http rather than